- doCompositorBasedDelete(): Sort list of deletion targets such that object whose eContainer() is not contained in 'targets' are deleted first (e.g., free connectors in hierarchical element models).
- This is required to avoid an NPE when the GUI is refreshed while the list of object to be deleted is processed.

refs 2231

refs 2262

refs 2304

refs 2304

- Ensure that in each session, the hint how to create new connections is displayed until the user has managed to create three of them.
- (Side note): The current implementation cannot distinguish connections created interactively by the user, and connections created by a model-transformations. However, we can assume that a user who is able to issue a model-transformation also knows how to create a channel in the GUI.
refs 2229

refs 2196

refs 2126

refs 2126

refs 2337

canPaste is checked inside canPasteInto to forbid pasting stated inside other states selected in the editor.
refs 2337

refs 2337

refs 2337

disabled Delete when trying to delete the background of the editor.
refs 2202

refs 2310

- Ignore update of IDs that may be triggered massively when saving a model that contains a lot of generated artifacts for which IDs are typically not assigned.
- Disabling the delivery of notifications during the assignment of IDs is not possible since the kernel needs to be notified about ID changes.	
refs 2309

refs 2309

- Delete also resources that contain references to the resource managed by the kernel (e.g., the AF3 project)
refs 2309

- This fixes the bug that the TreeMap suffers from collisions of identity hashes.
- The special properties of IdentityHashMap that it uses references equality (instead
  of equals()) to decide collisions is not needed here, but it also does not harm since
  this is the default implementation of equals(), and per definition there cannot be
  two equal elements (at the XMI resource level).
refs 2309

- Prefer the potentially a bit less efficient but safer Display.getDefault.syncExec() over Display.getDefault.asyncExec() to avoid NPEs triggered by model modifications
refs 2323

- Ensure that UI updates triggered from EMF notification mechanism are executed in the UI context (using Display.getDefault.asyncExec())
refs 2323

refs 2240

- Support sharing the ResourceSet used to load models managed by the kernel with additional model files (e.g., models, that are linked to the model managed by the kernel using IDs)
  - Save all resources in the ResourceSet when the model managed by the kernel is saved
  - Update ResourceSet when file used to persist Resource not managed by the kernel is removed from the file system
refs 2309

- Keep registration of these constraint checkers for FileProject objects in org.fortiss.af3.project
refs 2309

- Move internal.storage.Eclipse.AF3ResourceFactory -> utils.ResourceUtils.KernelResourceFactory
- Move registration of KernelResourceFactory for .af3_23 files to org.fortiss.af3.project
- Remove registration for .sfit files (should be handled in an appropriate plugin there)
refs 2309

 - In case the label could not be found, return a string representation of the value. This is useful to implement custom label providers for model elements are edited in combo boxes.
 - Prevent potential NPE

refs 2122

- Add IAnnotationValueProvider.isHidden() that allows to hide annotations from any view (useful for internal attributes that should not be exposed to the user). Default = false
- Extend AnnotationEntry and AnnotationFilter accordingly

- Prevent pollution of AnnotationEntry <-> IModelElement cache via instantiateAnnotations(final IModelElement element) (which might be invoked from model transformations). I.e., the cache is only updated, when the AnnotationEntries are queried from the GUI context.
- In case further measures need to be taken to limit the size of the AnnotationEntry <-> IModelElement cache, <http://stackoverflow.com/questions/2941283/java-fixed-memory-map> might be a good starting point

- Add RemoveUnknownFeatureMigrationProviderBase, a base class for {@link IMigrationProvider}s to selectively remove unknown features from a model.

- Instead of iteration over the entire model for each IIdLabeled element whose ID is to be checked for consistency and uniqueness, register the constraint checker for the FileProject and do each of the checks in one pass.
- Should fixes drastic performance problems introduced with last change to resolve this issue
refs 2309

- Add prefix "generated-" for directories of generated edit and editor code (not used in default AF3 distribution)

- By default, EMF uses fragment-path based links to persist EReferences. While this works fine for standalone model resources, it can cause inconsistencies in case there are multiple resource models that contain cross-resource references. (I.e., if the structure of the AF3 model resource changes, the links from the external model resource can become invalid)
- The recommended way to work around this is to configure EMF to use IDs to encode EReferences.

Solution:
- Change persistence of AF3 model resources to encode references using an (extrinsic) xmi:id, that is identical to the model element's org.fortiss.tooling.kernel.model.IIdLabled.id. A dedicated XMIResource type for AF3 model resources is used (which is created by a resource factory registered for *.af3_23 files)
- The reason for not using IIdLabled.id as intrinsic ID is that the implemented solution using xmi:id is both forward and backward compatible
- At the price of losing forward compatibility, the IIdLabled.id could be changed to a derived, volatile EAttribute that simply returns the value of xmi:id
- Add EContentAdapter to sync xmi:id and IIdLabled.id
- Ensure uniqueness of IDs (that is now much more crucial) during when loading and saving as well as importing and exporting models (and print a warning to the console in case duplicates have been detected and fixed)
- As an additional safety layer, add constraint checkers to ensure uniqueness of IDs and consistency of IIdLabled.id and xmi:id

Related changes:
- Speed up loading and saving of XMI resources by setting corresponding XMLResource options
- Ensure that IDs are assigned to annotations as soon as they are instantiated
refs 2309

- GSNPositionedEditPartBase*: Avoid code duplication by pushing refreshDecorationFigure() to PositionedEditPartBase
- PositionedEditPartBase.refreshDecorationFigure()
  - Avoid SWT Image leak by reusing the same icons
  - Add more null-checks to implementation
- MarkerViewPart -> column updater: Avoid SWT Image leak by disposing old image before setting a new one